The present invention relates to an ink ejectability maintenance device for maintaining constant ink ejectability of a recording head for ejecting ink droplets toward a recording medium, as well as to a recording apparatus equipped with the ink ejectability maintenance device.
An ink jet printer, which is one example of the recording apparatus, is usually equipped with a print head mounted on a carriage which travels back and forth in a main scanning direction, and a medium feeder for intermittently feeding a recording medium, such as print paper, in a sub-scanning direction in preset increments. The print head is actuated in the main scanning direction while the recording medium is being fed in the sub-scanning direction, and ink droplets are ejected toward the recording medium from the print head.
A mono-color ink jet printer is usually equipped with one print head. In contrast, a full-color ink jet printer is equipped with a black-ink print head for ejecting black ink, and a plurality of color-ink print heads for ejecting various colors of ink, such as yellow, cyan, and magenta.
A print head of an ink jet printer of such a construction has a pressure generation chamber and a nozzle orifice communicated therewith. Ink is stored in a pressure generation chamber and pressurized at a predetermined pressure, whereby ink droplets of controlled size are ejected from the nozzle orifice to the recording medium. Accordingly, when variations arise in the ink ejectability of the nozzle orifice of the print head, the quality of a recorded image is greatly affected. Hence, the ink ejectability must be maintained constant at all times.
The ink ejectability is changed by various phenomena, such as an increase in viscosity or solidification due to evaporation or drying of solvent in ink by way of the nozzle orifice, clogging due to solid material, adhesion of dust to the nozzles, and intrusion of air bubbles into ink. In order to prevent occurrence of such a change in characteristic, the ink jet printer is equipped with an ink ejectability maintenance device which eliminates the above-described phenomena causing variations to maintain the ink ejectability constant.
The ink ejectability maintenance device is equipped with a capping device, a suction pump, and a wiping device. The capping device is arranged so as to seal a nozzle formation face of a print head when no recording operation is performed, thereby isolating the nozzle orifice from the outside. Thus, the ink ejectability maintenance device has the function of inhibiting evaporation and drying of ink, thereby hindering an increase in viscosity and solidification of ink. Even when the nozzle formation face is sealed with the capping device, there cannot be completely prevented occurrence of clogging due to solid material in the nozzle orifice or intrusion of air bubbles into an ink flow channel. The ink jet printer is further equipped with a suction pump for the purpose of completely preventing occurrence of these problems.
The suction pump is configured so as to exert negative pressure on the nozzle orifice while the nozzle formation face is sealed with the capping device. The suction pump has the function of forcefully causing ink to be discharged from the nozzle orifice through suction, thereby eliminating solid material or air bubbles. Forceful discharge of ink to be performed by the suction pump is usually carded out when a recording operation is resumed after the ink jet printer has remained inoperative for a long time period or when the user has actuated a specifically-designed switch provided in a control panel with the understanding that deterioration of recorded image quality.
When ink is forcefully discharged by the suction pump, ink may splash across a nozzle formation face of the printer head, and in each nozzle orifice an ink meniscus may be disturbed. The nozzle formation face of the print head becomes susceptible to adhesion of extraneous matter with lapse of time. Hence, the print head is equipped with a wiping device for wiping the nozzle formation faces as required,
The wiping device has a wiping member whose base end is caught by a holder, and is constituted of an elastic plate such as rubber, An edge of the extremity of the wiping member is elastically pressed against a nozzle formation face, thereby effecting relative reciprocal movement so as to wipe the nozzle formation face As a result, ink or extraneous matter adhering to the nozzle formation face is wiped, and ink meniscuses of respective nozzle orifices are made uniform. In shoo, the wiping device has the function of making the nozzle formation face stable.
As described in Japanese Patent Publication No. 11-138830A, a related-art ink ejectability maintenance device switches between driving of a capping device and a wiping device and driving of a suction pump, through use of a single planetary gear in accordance with the rotating direction of a motor which acts as a drive source.
In the ink jet printer equipped with the related-art ink ejectability maintenance device, the capping device and the wiping device are arranged in the same direction or are slightly offset from each other; namely, in an overlapping manner, in order to suppress an increase in the size of a recording apparatus with respect to the scanning direction of a carnage. In order to prevent occurrence of interference between the wiper and the cap, there has been adopted a mechanism for reciprocally actuating the wiper in the wiping direction of the wiping device while the cap is held down, or a mechanism for reciprocally actuating the wiper and the cap in the wiping direction.
The former mechanism requires a large amount of vertical movement of the cap for preventing occurrence of interference between the cap and the wiper. Hence, the size of the capping device is increased in the sealing direction. Moreover, if the wiper is arranged so as to avoid interference between the wiper and the cap, the size of the wiping device is increased in is the scanning direction of the carriage.
If an attempt is made to perform a flushing operation in which ink is ejected within the cap during, before, or after a printing operation and to seat the nozzle with the cap after the printing operation, moisture contained in a head surface or the nozzle is absorbed by the ink after the ink has dried. Consequently, the viscosity of ink stored in the nozzle is increased, which in turn deteriorates print quality after the printer has been left for a while. Since ink accumulates in the cap during a long-time printing operation, there may arise a necessity for an operation of discharging ink from the cap during the course of a printing operation.
By the latter mechanism, the cap and the wiper are actuated together. Hence, the size of the mechanism is increased in the wiping direction. In a case where a flushing operation is performed in the space from which the cap and the wiper have departed, a distance between the nozzle and an absorbing material for receiving flushed ink becomes longer. As a result, minute ink droplets (i.e., ink mist) waft through the space, possibly contaminating the paper transport path and the exterior of the printer.
It is therefore an object of the present invention to provide an ink ejectability maintenance device capable of preventing contamination, which would otherwise be caused by ink mist stemming from flushing, as well as a recording apparatus equipped with the ink ejectability maintenance device.
In order to achieve the above object, according to the present invention, there is provided an ink ejectability maintenance device for maintaining an ink ejectability of a recording head which ejects ink droplets to a recording medium, comprising:
a wiper, having a first moving path extending in a first direction in which the recording medium is fed, to wipe a nozzle formation face of the recording head;
a cap, having a second moving path extending in a vertical direction to seal the nozzle formation fare; and
an absorption member, disposed below the first moving path to receive and absorb ink therein, wherein:
the first moving path is away from the sand moving path in connection with a second direction perpendicular to the first direction; and
a first horizontal plane in which the wiper is placed and a second horizontal plane in which the cap is placed are away from each other in the vertical direction.
In this devices a reduction in the size of the cap in the vertical direction while the amount of movement of the cap in the vertical direction can be minimized. Ink droplets are immediately absorbed by the absorption member without involvement of occurrence of an ink mist even when a flushing operation is performed. Further, ink droplets which have run from the wiper are absorbed immediately. Hence, there can be prevented contamination of a recording medium transporting path or an exterior of the recording apparatus.
Preferably, the ink ejectability maintenance device further comprises a driver unit including a pair of planetary gears which transmits a driving force thereof to the wiper and the cap, and a single rotor which rotates either one of the planetary gears so that the driving force is transmitted by both of a forward rotation and a reverse rotation thereof.
In this device, the cap and the wiper can be actuated independently of each other. Hence, the amount of movement of the cap in the vertical direction is minimized, and the size of the cap in the vertical direction can be reduced.
Here, it is preferable that the driver unit includes a sun gear meshed with the respective planetary gears and a partially-chipped gear connected to the wiper. The partially-chipped gear includes a cog portion which meshes either one of the planetary gears when the wiper is moved, and a cogless portion which faces either one of the planetary gears after the wiper is moved.
In this device, actuation of the cap and actuation of the wiper can be performed regardless of whether the rotor rotates forward or in reverse. Hence, the position of the cap or that of the wiper can be readily initialized. Consequently, there is obviated a necessity for setting, on a cam for actuating the cap and the wiper, a flag to be used for detecting the position of the cap and that of the wiper for initialization purpose, which has hitherto been used. Hence, an attempt can be made to facilitate assembly and adjustment of the ink ejectability maintenance device or curtail costs of the device. Further, the cap and the wiper can be placed in predetermined positions without fail by rotating merely the partially-chipped gear to the cogless portion by the planetary gear.
Here, it is preferable that the partially-chipped gear is a four-gears unit which respectively meshes the respective planetary gears, a wiper gear for driving the wiper, and a cap gear for driving the cap.
In this device, the torque of each of the planetary gears can be transmitted to the wiper gear and the cap gear thoroughly. Hence, the positioning accuracy of the cap and that of the wiper can be improved, and capping and wiping operations can be performed independently.
Here, it is preferable that the wiper gear includes a lever and a cam mechanism for moving the wiper in the first direction, and the cap gear includes a cam mechanism for moving the cap in the vertical direction.
In this device, since the wiper and the cap, which have the well-known lever and cam mechanism, the labor required for changing design can be simplified.
Preferably, the ink ejectability maintenance device further comprises a suction unit which applies negative pressure to an internal space of the cap which seals the nozzle formation face. Here, the suction unit is activated after the driver unit drives the wiper and the cap.
In this device, the suction unit is activated by rotation of the rotor in either direction. Particularly when a tube pump is employed, a pulley can be released from the tube. The tube can be prevented from remaining collapsed by the pulley without use of a special mechanism. Since capping can be effected without driving of a pump, the pump tube is not collapsed even when the capping unit is opened and closed before and after printing.
According to the present invention, there is also provided a recording apparatus comprising the above ink ejectability maintenance device.